Late start of eating is linked to lower insulin sensitivity and hyperinsulinemia in prediabetes

Background: Prediabetes is associated with an increased risk of progression to type 2 diabetes. While dietary interventions in prediabetes traditionally focus primarily on energy and macronutrient intake, the role of eating timing has recently been highlighted. This study aimed to examine the relationships between eating timing pattern and glycaemic parameters in prediabetes. Methods: 297 individuals with prediabetes, i.e. impaired fasting glucose or impaired glucose tolerance (age 59.5 y, BMI 31.3 kg/m2), underwent detailed metabolic phenotyping including an oral glucose tolerance test and magnetic resonance imaging/spectroscopy. Parameters of temporal eating pattern (eating timing, daily calorie distribution, and meal number) were extracted from four-day food records. Eating start (ES) was defined as the start of the first caloric event of the day. Results: Among eating timing parameters, ES showed the most associations with glycaemic traits. Each later hour of ES was associated with a 0.88 mU/l higher fasting insulin (95% CI, 0.13 to 1.64 mU/l), a 16.17 mU/l higher 120 min insulin (95% CI, 5.91 to 26.44 mU/l), a 1061 mU/l*min higher AUC insulin (95% CI, 357 to 1764 mU/l*min),a 0.30 units higher HOMA-IR (95% CI, 0.10 to 0.50), and a -0.15 units lower Matsuda insulin sensitivity index (95% CI, -0.28 to -0.02) after adjustment for age, sex, and daily energy intake, as well as food composition. Glycemic associations remained after additional adjustment for body fat percentage, which was increased in individuals with later ES (0.81% per ES hour; 95% CI, 0.27 to 1.34%). No associations of eating timing with visceral or liver fat were found. Conclusion: Late ES is associated with estimates of hyperinsulinemia and lower insulin sensitivity in prediabetes, independent of energy intake, food composition, and body fat. Earlier ES might relate to improved glucose metabolism and lower the risk of progression to diabetes.